arXiv subjects

A. García-Cristóbal

Publications and source records attributed to A. García-Cristóbal.

4 recordsLinked to original sources

arXiv2019

Topology driven g-factor tuning in type-II quantum dots

We investigate how the voltage control of the exciton lateral dipole moment induces a transition from singly to doubly connected topology in type II InAs/GaAsSb quantum dots. The latter causes visible Aharonov-Bohm oscillations and a change of the exciton g-factor which are modulated by the applied bias. The results are explained in the frame of realistic $\mathbf{k}\cdot\mathbf{p}$ and effective Hamiltonian models and could open a venue for new spin quantum memories beyond the InAs/GaAs realm.

cond-mat.mes-hall↗

arXiv2016

The generalized plane piezoelectric problem: Theoretical formulation and application to heterostructure nanowires

We present a systematic methodology for the reformulation of a broad class of three-dimensional (3D) piezoelectric problems into a two-dimensional (2D) mathematical form. The sole underlying hypothesis is that the system geometry and material properties as well as the applied loads (forces and charges) and boundary conditions are translationally invariant along some direction. This class of problems is commonly denoted here as the generalized plane piezoelectric (GPP) problem. The first advantage of the generalized plane problems is that they are more manageable from both analytical and computational points of view. Moreover, they are flexible enough to accommodate any geometric cross section, crystal class symmetry, axis orientation and a wide range of boundary conditions. As an illustration we present numerical simulation of indefinite lattice-mismatched core-shell nanowires made of diamond Ge/Si and zincblende piezoelectric InN/GaN materials. The remarkable agreement with exact 3D simulations of finite versions of those systems reveal the GPP approach as a reliable procedure to study accurately and with moderate computing resources the strain and electric field distribution in elongated piezoelectric systems.

cond-mat.mes-hall↗

arXiv2016

Optical properties of wurtzite GaN/AlN quantum dots grown on non-polar planes: the effect of stacking faults in the reduction of the internal electric field

The optical emission of non-polar GaN/AlN quantum dots has been investigated. The presence of stacking faults inside these quantum dots is evidenced in the dependence of the photoluminescence with temperature and excitation power. A theoretical model for the electronic structure and optical properties of non-polar quantum dots, taking into account their realistic shapes, is presented which predicts a substantial reduction of the internal electric field but a persisting quantum confined Stark effect, comparable to that of polar GaN/AlN quantum dots. Modeling the effect of a 3 monolayer stacking fault inside the quantum dot, which acts as zinc-blende inclusion into the wurtzite matrix, results in an additional 30 % reduction of the internal electric field and gives a better account of the observed optical features.

cond-mat.mes-hall↗

arXiv2013

LDA+U and tight-binding electronic structure of InN nanowires

In this paper we employ a combined {\it ab initio} and tight-binding approach to obtain the electronic and optical properties of hydrogenated InN nanowires. We first discuss InN band structure for the wurtzite structure calculated at the LDA+U level and use this information to extract the parameters needed for an empirical tight-binging implementation. These parameters are then employed to calculate the electronic and optical properties of InN nanowires in a diameter range that would not be affordable by {\it ab initio} techniques. The reliability of the large nanowires results is assessed by explicitly comparing the electronic structure of a small diameter wire studied both at LDA+U and tight-binding level.

cond-mat.mes-hall↗